The term 'certification' covers a multitude of aspects:-
The 'price' of implementation? - it's different for each organization
The 'price' of the CB audit? - should be fairly similar in each 'region'
The 'price' of the certificate? (some CB's don't charge a 'certificate fee')
Ultimately, the customer/market 'regulates' the price.
Or you can consider the 'price' to a business of not being certified...